How many 2x8 floor joists will you need for a 12x16 floor?

To determine the number of 2x8 floor joists needed for a 12x16 floor, first calculate the area of the floor, which is 192 square feet (12 feet x 16 feet). Assuming the joists are spaced 16 inches apart on center, you will need about 12 joists running the 16-foot length (16 feet = 192 inches; 192 inches ÷ 16 inches = 12). Therefore, you will need approximately 12 joists to support the floor.